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Published April 2021 | Published
Journal Article Open

Low Noise Amplifier With 7-K Noise at 1.4 GHz and 25 °C


This article describes a low noise amplifier which is believed will have a transformative impact because of the following characteristics: 1) the noise temperature at a physical temperature of 25 °C is a factor of 4 lower than typical commercial LNAs; 2) the noise decreases to 4.5 K at a temperature of -40 °C, a temperature realizable with solid-state coolers; 3) the LNA has an integrated, extremely stable noise source to facilitate measurement of system noise temperature; and 4) the amplifier is powered by a dc voltage and controlled by a tone signal on the RF output cable thus requiring no additional wiring. The amplifier benefits systems in the low microwave frequency range with low background temperature, such as those for space communications and radio astronomy, but without the capital and maintenance costs of cryogenic systems. This article describes the construction and test results with an emphasis on the manufacturability and accuracy of the noise measurements. Finally, the noise of a system deploying the LNA is described.

Additional Information

© 2021 IEEE. This work is licensed under a Creative Commons Attribution 4.0 License. Manuscript received November 8, 2020; revised January 4, 2021 and January 18, 2021; accepted January 25, 2021. Date of publication March 10, 2021; date of current version April 2, 2021. This work was supported by the U.S. National Science Foundation under Grant NSF 1836018. Sander Weinreb and Jun Shi, joint first authors, contributed equally to this work. The authors would like to thank David Hodge and Hector Navarrete for much of the assembly work, Ralf Fluckiger for the excellent transistors, and Hamdi and Houssem Mani for suggestions and machining of the modules.

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